Expandable spinal implant

ABSTRACT

An expandable spinal implant configured for positioning within the intervertebral space between adjacent vertebral bodies is disclosed. The spinal implant includes a first body, a second body, a ratchet, and a locking mechanism. The first and second bodies are pivotably affixed to each other on respective first ends thereof and are capable of movement relative to each other in a medial-lateral direction with respect to the adjacent vertebral bodies. The ratchet is pivotably supported within a slot defined in the first body and is capable of engaging the second body thereby permitting movement of the first and second body relative to each other in a first direction, but not in a second direction that is different than the first direction. A method of performing spinal surgery is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 14/464,892, filed on Aug. 21, 2014, which claimspriority to, and the benefit of, U.S. Provisional Patent ApplicationSer. No. 61/868,499, filed on Aug. 21, 2013, the entire contents of eachof which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to devices and methods fortreating spinal conditions, and in particular, to expandable spinalimplants configured for positioning within an intervertebral space.

BACKGROUND

The human spine includes thirty-three vertebrae. The vertebrae interlockwith one another to form a spinal column. Each vertebra has acylindrical bony body (vertebral body), two pedicles extending from thevertebral body, a lamina extending from the pedicles, two wing-likeprojections extending from the pedicles, a spinous process extendingfrom the lamina, a pars interarticularis, two superior facets extendingfrom the pedicles, and two inferior facets extending from the lamina.The vertebrae are separated and cushioned by thin pads of tough,resilient fiber known as intervertebral discs. Intervertebral discsprovide flexibility to the spine and act as shock absorbers duringactivity. A small opening (foramen) located between each vertebra allowspassage of nerves. When the vertebrae are properly aligned, the nervespass through without a problem. However, when the vertebrae aremisaligned or a constriction is formed in the spinal canal, the nervesget compressed and may cause back pain, leg pain, or other neurologicaldisorders.

Disorders of the spine that may cause misalignment of the vertebrae orconstriction of the spinal canal include spinal injuries, infections,tumor formation, herniation of the intervertebral discs (i.e., slippageor protrusion), arthritic disorders, and scoliosis. In these pathologiccircumstances, surgery may be tried to either decompress the neuralelements and/or fuse adjacent vertebral segments. Decompression mayinvolve laminectomy, discectomy, or corpectomy. Laminectomy involves theremoval of part of the lamina, i.e., the bony roof of the spinal canal.Discectomy involves removal of the intervertebral discs. Corpectomyinvolves removal of the vertebral body as well as the adjacentintervertebral discs.

The time-honored method of addressing the issues of neural irritationand instability resulting from severe disc damage have largely focusedon removal of the damaged disc and fusing the adjacent vertebralelements together. Removal of the disc relieves the mechanical andchemical irritation of neural elements, while osseous union (boneknitting) solves the problem of instability.

While cancellous bone appears ideal to provide the biologic componentsnecessary for osseous union to occur, it does not initially have thestrength to resist the tremendous forces that may occur in theintervertebral disc space, nor does it have the capacity to adequatelystabilize the spine until long term bony union occurs. For thesereasons, many spinal surgeons have found that interbody fusion usingbone alone has an unacceptably high rate of bone graft migration,expulsion, or nonunion due to structural failures of the bone orresidual degrees of motion that retard or prohibit bony union.Therefore, intervertebral prostheses in various forms have been used toprovide immediate stability and to protect and preserve an environmentthat fosters growth of grafted bone such that a structurally significantbony fusion can occur.

Many intervertebral implants have one or more fixed dimensions that maycreate challenges and/or lead to compromises when selecting a suitableimplant for a surgical procedure.

Therefore, a need exists for an expandable spinal implant that can beinserted in a collapsed state in order to prevent over retraction of theanatomy, a reduction in surgical morbidity, and/or substandard implantsizing. Once the expandable spinal implant is in place, it can then beexpanded to fill the anatomical space appropriately.

SUMMARY

In accordance with the present disclosure, a spinal implant including afirst body, a second body, and a ratchet mechanism is provided. Thefirst and second bodies are pivotably affixed to each other atrespective first ends thereof and are capable of movement relative toeach other. The first and second bodies are dimensioned to be installedbetween two vertebral bodies and the outer surfaces of each of the firstand second bodies are adapted to engage the vertebral bodies. Themovement of the first and second bodies is in a medial-lateral directionrelative to the two vertebral bodies. A ratchet mechanism is pivotablysupported within a slot defined in a recess of the first body. Theratchet mechanism is capable of engaging a portion of the second bodythereby permitting movement of the first and second bodies relative toeach other in a first direction, and inhibiting movement in a seconddirection different than the first direction.

In aspects, outer surfaces of the first body and the second body includeridges adapted to engage the first and second vertebral bodies.

In aspects, at least one biasing element is disposed within acounterbore defined in the recess of the first body. The at least onebiasing element is adapted to bias the ratchet mechanism into engagementwith the second body.

In aspects, the ratchet mechanism includes a first plurality of teethdisposed thereon.

In aspects, the second body includes a second plurality of teethdisposed on an interior surface thereon opposite the ratchet mechanism.The second plurality of teeth is configured to engage the firstplurality of teeth of the ratchet mechanism.

In aspects, the first and second pluralities of teeth are oriented suchthat the first and second pluralities of teeth are slidably engaged in afirst direction, and are prohibited from movement relative each other ina second direction different from the first direction, thereby defininga predetermined size of the spinal implant.

In aspects, the spinal implant further includes a locking mechanismdisposed within an orifice defined in a side surface of the ratchetmechanism and a keyhole defined in an end face of the second body.

In aspects, the locking mechanism includes first and second ends,wherein the second end is capable of advancing axially within thekeyhole in a first, unlocked position. The second end is also capable oflocking the ratchet mechanism into a selected position when in a second,locked, position.

In aspects, the spinal implant is capable of being inserted between twovertebral bodies using a tool.

In aspects, the first and second bodies are capable of being manipulatedrelative to each other using a tool.

In aspects, the first end of the locking mechanism is attachable to atool.

A method of performing surgery provided in accordance with the presentdisclosure includes providing a spinal implant comprising a first body,a second body, and a ratchet mechanism. The first and second bodies arepivotably affixed to each other at respective first ends thereof and arecapable of movement relative to each other. The first and second bodiesare dimensioned to be installed between two vertebral bodies and theouter surfaces of each of the first and second bodies are adapted toengage the vertebral bodies. The movement of the first and second bodiesmay be in a medial-lateral direction relative to the two vertebralbodies. A ratchet mechanism is pivotably supported within a slot definedin a recess of the first body. The ratchet mechanism is capable ofengaging a portion of the second body thereby permitting movement of thefirst and second bodies relative to each other in a first direction, andinhibiting movement in a second direction different than the firstdirection. The method further includes positioning the first body andthe second body in a first, approximated position relative each other,preparing an intervertebral space between first and second vertebralbodies to receive the spinal implant, inserting the spinal implant intothe prepared intervertebral space, articulating the first body and thesecond body relative to each other to obtain a desired medial-lateralfootprint within the intervertebral space, and locking the ratchetmechanism to define a predetermined size of the spinal implant.

In aspects, inserting the spinal implant includes first securing thespinal implant to an insertion device.

In aspects, locking the ratchet mechanism includes rotating a lockingmechanism disposed within an orifice defined within a side surface ofthe ratchet mechanism and a keyhole defined in an end face of the secondbody. The locking mechanism includes first and second ends, and iscapable of advancing axially within the keyhole. Rotating the toolcauses the locking mechanism to rotate to a locked position.

In aspects, positioning the first body and second body in a first,approximated, position includes engaging a first plurality of teethdisposed on a surface of the ratchet mechanism with a second pluralityof teeth disposed on an opposing surface of other one of the first bodyand second body, thereby permitting articulation of the first bodyrelative to the second body in a first direction, but not in a seconddirection.

In aspects, inserting the spinal implant includes attaching an insertioninstrument to the spinal implant.

In aspects, articulating the first body relative to the second bodyincludes manipulating an insertion instrument, thereby causing the firstbody and the second body to articulate relative to each other.

In aspects, locking the ratchet mechanism further includes attaching atool to a first end of the locking mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is an exploded view, with parts separated, of an expandablespinal implant provided in accordance with the present disclosure;

FIG. 2 is a top view of the expandable spinal implant of FIG. 1, shownin a closed position;

FIG. 3 is an end view of the expandable spinal implant of FIG. 1, shownin the closed position;

FIG. 4 is a side view of the expandable spinal implant of FIG. 1, shownin the closed position;

FIG. 5 is a top view of the expandable spinal implant of FIG. 1, shownin an expanded position;

FIG. 6 is an end view of the expandable spinal implant of FIG. 1, shownin an expanded position;

FIG. 7 is a side view of the expandable spinal implant of FIG. 1, shownin an expanded position;

FIG. 8 is an enlarged view of a locking mechanism of the expandablespinal implant of FIG. 1, shown in an unlocked position;

FIG. 9 is an enlarged view of the locking mechanism of FIG. 8, shown ina locked position;

FIG. 10 is a plan view of an intervertebral space shown with twoexpandable spinal implants of FIG. 1 in a closed position; and

FIG. 11 is a plan view of the intervertebral space of FIG. 10, shownwith two expandable spinal implants of FIG. 1 in an expanded position.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. Asused herein, the term “clinician” refers to a doctor, a nurse or anyother care provider and may include support personnel. Throughout thisdescription, the term “proximal” will refer to the portion of the deviceor component thereof that is closer to the clinician and the term“distal” will refer to the portion of the device or component thereofthat is farther from the clinician. Additionally, in the drawings and inthe description that follows, terms such as front, rear, upper, lower,top, bottom, and similar directional terms are used simply forconvenience of description and are not intended to limit the disclosure.In the following description, well-known functions or constructions arenot described in detail to avoid obscuring the present disclosure inunnecessary detail.

Referring now to the drawings, FIG. 1 illustrates an embodiment ofexpandable spinal implant 10 provided in accordance with the presentdisclosure. Expandable spinal implant 10 includes a first body 100, asecond body 200, a ratchet mechanism 300, a locking mechanism 400,biasing elements 500, and hinge pins 600. First and second bodies 100,200 cooperate to define a two part expandable spinal implant configuredfor positioning between adjacent vertebral bodies. Ratchet mechanism 300and locking mechanism 400 cooperate to provide a locking mechanism tolock first and second bodies 100, 200 in an expanded position relativeto each other, thereby expanding the medial-lateral footprint ofexpandable spinal implant 10. Each of these components along with theassembly and insertion of expandable spinal implant 10 into theintervertebral space, as well as the expansion/contraction of expandablespinal implant 10 within the intervertebral space will be described inturn hereinbelow.

The various components of expandable spinal implant 10, or portionsthereof, may be formed from various similar or different materials,depending on a particular purpose. In particular, first and secondbodies 100, 200 may be formed from a metallic material (e.g., titanium,titanium alloy, or cobalt chrome (CoCr)) or a non-metallic material(e.g., polymeric materials such as polyetheretherketone (PEEK),non-absorbable polymers, nylon absorbable polymers such aspolyglycolides, polylactides, polycaprolactone, etc., or organicmaterials such as bone) and ceramic materials. Ratchet mechanism 300,locking mechanism 400, biasing elements 500, and hinge pins 600 may beformed from titanium, titanium alloy, CoCr or other suitable metal orpolymeric material compatible with first and second bodies 100, 200.

With reference to FIGS. 1, 2, and 8, expandable spinal implant 10 isillustrated. Expandable spinal implant 10 is formed by first and secondbodies 100, 200, which are operable to be positioned in an expandedstate (FIG. 5), or a closed state (FIG. 2). Expandable spinal implant 10includes substantially contoured first end surfaces 12 a, 12 b at adistal or leading end 14 a, 14 b of first and second bodies 100, 200,respectively, and second end surfaces 16 a, 16 b opposite thereto at aproximal or trailing end 18 a, 18 b, of first and second bodies 100,200, respectively. Expandable spinal implant 10 extends between thefirst and second end surfaces 12 a, 12 b and 16 a, 16 b to definerespective top and bottom surfaces 20 a, 20 b, 22 a, and 22 b, as wellas opposed side surfaces 24, 26. As illustrated in FIG. 3, the top andbottom surfaces 20 a, 20 b and 22 a, 22 b, engage side surfaces 24, 26,respectively, to provide a substantially rectangular cross-sectionalprofile, with rounded corners 27 a, 27 b. As best illustrated in FIGS. 2and 4, first end surfaces 12 a, 12 b form a substantially atraumaticblunt nose profile, and second end surfaces 16 a, 16 b form asubstantially flat or planar profile. For a more detailed discussion ofthe profile of expandable spinal implant 10, reference may be made toU.S. Pat. No. 8,801,791, filed on Sep. 27, 2007, entitled “SpinalInterbody Spacer,” the entirety of which is incorporated herein byreference.

Referring now to FIGS. 3 and 4, top surfaces 20 a, 20 b are generallyshown as being angled with respect to bottom surfaces 22 a, 22 b in adirection from leading end 14 to trailing end 18 thereby defining alordotic taper capable of effectuating lordosis of the spine whenexpandable spinal implant 10 is advanced within the intervertebralspace. Although generally shown as being angled with respect to eachother such that the trailing end 18 has a height that is less than aheight of the leading end 14, it is contemplated that top surfaces 20 a,20 b and bottom surfaces 22 a, 22 b may be angled with respect to eachother such that leading end 14 has a height that is less than a heightof the trailing end 18. It is also contemplated that top surface 20 maybe parallel to bottom surface 22.

As illustrated in FIGS. 1 and 4, top and bottom surfaces 20 a, 20 b, 22a, and 22 b define a first plurality of ridges 30 a and a secondplurality of ridges 30 b arranged thereon. The first plurality of ridges30 a are disposed proximate to leading ends 14 a, 14 b and the secondplurality of ridges 30 b are disposed proximate to trailing ends 18 a,18 b, each of which are configured to frictionally engage an adjacentsurface of a vertebral body VB (i.e., a vertebral endplate) to preventexpandable spinal implant 10 from backing out of the intervertebralspace since the ridges 30 a and 30 b will bite into the adjacentvertebral plate. First and second pluralities of ridges 30 a, 30 binclude distinct profiles (i.e., first plurality of ridges 30 a may havean elongate triangular profile, while second plurality of ridges 30 bmay have a pyramidal profile); however, it is contemplated that firstand second pluralities of ridges 30 a, 30 b may have similar profiles.For a detailed discussion of the construction of exemplary ridges,reference may be made to U.S. Pat. No. 8,801,791, filed on Sep. 27,2007, entitled “Spinal Interbody Spacer,” the entirety of which isincorporated herein by reference.

Referring now to FIGS. 1 and 5, an illustration of first body 100 isshown. Channel 102 is defined through first and second end surfaces 12a, 16 a and is substantially parallel to side surface 24; however, it iscontemplated that channel 102 may approximate side surface 24 in adirection from trailing end 18 a towards leading end 14 a and viceversa. Although generally shown as having a substantially U-shapedconfiguration, it is contemplated that channel 102 may have othersuitable cross sections, such as v-shaped, circular, or oval.

Relief 104 (FIG. 5) is illustrated as being defined through top andbottom surfaces 20 a, 22 a adjacent to leading end 14 a, and definesfaces 106, 108, extending substantially perpendicular to top and bottomsurfaces 20 a, 22 a. Counterbores 110 are defined in face 106 and areconfigured and/or dimensioned to receive biasing elements 500, such thatbiasing elements 500 bias ratchet mechanism 300 into engagement withteeth 208 of second body 200, thereby permitting motion in a firstdirection, and inhibiting motion in a second, opposite direction. Pivotslot 112 is defined in face 108 and is open at the top and bottomsurfaces 20 a, 22 a. Pivot slot 112 includes a circular cross sectionwith less than half of the circumference open such that pivot 304 ofratchet mechanism 300 is rotatably secured therein.

Counterbores 114 are defined within each of the upper and lower innersurfaces of channel 102, adjacent to trailing end 18 a and side surface24. Through-holes 116 are defined through upper surface 20 a and lowersurface 22 a and are concentric with counterbore 114. Through-holes 116are configured to frictionally retain hinge pins 600 therein.

With reference to FIG. 4, slot 118 is defined through side surface 24and includes an elongate shape complimentary to that of side surface 24of first body 100; however, it is contemplated that slot 118 may includeother suitable shapes such as circular, rectangular, or the like. It isfurther contemplated that slot 118 may include a plurality of individualapertures.

Referring back to FIGS. 1 and 5, an illustration of second body 200 isshown generally as having a shape complimentary to that of first body100 (i.e., mirrored) and thus, in the interest of brevity, only thedifferences between first body 100 and second body 200 will be detailedherein. Extension 204 extends from inner face 202 (adjacent to leadingend 14 b) and terminates in end face 206 (FIG. 5). Teeth 208 aredisposed on an opposing face to that of first end surface 12 b and areconfigured to engage teeth 306 of ratchet mechanism 300 such that whenin an unlocked position, first body 100 and second body 200 may pivot orrotate relative to each other in a first direction causing expandablespinal implant 10 to expand, but not in a second direction allowingexpandable spinal implant 10 to contract (i.e., a direction causingfirst and second bodies 100, 200 to approximate each other). Teeth 208are generally shown as being arranged in an arcuate profile (when viewedlooking towards top surface 20 b); however, it is contemplated thatteeth 208 may have other suitable profiles, such as planar. Keyhole 210(FIG. 8) is defined through end face 206 and includes a circular crosssection and an intersecting rectangular cross section such that keyhole210 is defined through teeth 208. Keyhole 210 is configured to receiveleading end 414 of locking mechanism 400.

Counterbores 212 are disposed within top and bottom surfaces 20 b, 22 bof second body 200 adjacent to trailing end 18 b and are complimentaryto counterbores 114 of first body 100 such that counterbores 114 and 212interlock (i.e., counterbores 212 pass within counterbores 114).Through-bore 214 is defined through top and bottom surfaces 20 b, 22 band is concentric with counterbores 212. Through-bore 214 is configuredand/or dimensioned to rotatably receive hinge pins 600 therein, suchthat hinge pins may be pressed into through-hole 116 (held in frictionalengagement) and pass through through-bore 214 such that first and secondbodies 100, 200 are pivotably/rotatably retained thereabout. Hinge pins600 may be any suitable pin, such as a dowel pin, a roll pin, or thelike.

Aperture 216 (FIG. 5) is defined through top and bottom surfaces 20 b,22 b at a location where first end surface 14 b and side surface 26intersect.

Continuing with FIGS. 1 and 5, an illustration of ratchet mechanism 300is shown. Ratchet mechanism 300 includes first and second ends definingelongate body 302 therebetween. Pivot 304 is disposed on the first endof elongate body 302 and includes a substantially circular cross sectionextending from upper surface 302 a to lower surface 302 b. Pivot 304 isconfigured and/or adapted to be received within pivot slot 112 of firstbody 100 such that ratchet mechanism 300 is pivotably secured therein.Boss 316 extends from a side surface 302 c adjacent to pivot 304 and isconfigured to engage biasing elements 500, thereby biasing ratchetmechanism 300 into engagement with teeth 208 of second body 200, therebypermitting motion in a first direction, and inhibiting motion in asecond, opposite direction. Teeth 306 are disposed on a second, opposingside surface and are configured to engage teeth 208 of second body 200.Teeth 306 are arranged in a profile complimentary to that of teeth 208of second body 200, such as arcuate; however, it is contemplated thatteeth 306 may be arranged in any suitable profile that is complimentaryto that of the profile of teeth 208. Orifice 308 is defined through sidesurface 302 c and teeth 306, and is configured to receive lockingmechanism 400 such that locking mechanism 400 is rotatably securedtherein. Bore 310 is defined through side surface 302 c proximate toorifice 308 and is configured to frictionally retain limiting pin 312therein. Limiting pin 312 may be any suitable pin, such as a dowel, aroll pin, or the like, and is disposed within bore 310, thereby limitingthe rotational motion of locking mechanism 400. Retaining bore 314 isdefined through upper surface 302 a and intersects a portion of orifice308, such that when retaining pin 318 is frictionally retained therein,locking mechanism 400 is prevented from advancing axially in orifice308. Retaining pin 318 may be any suitable pin, such as a dowel, a rollpin, or the like.

An illustration of locking mechanism 400 is shown in FIGS. 1, 8 and 9.Locking mechanism 400 includes an elongate body 402 including first andsecond ends. The first end of elongate body 402 includes a hexagonalcross section 404. Hexagonal cross section 404 includes annular groove404 a defined therein capable of engaging a suitable tool (not shown).Hexagonal cross section 404 transitions to a flange 406 having acircular cross section extending in a direction towards the second end.Flange 406 includes a larger diameter than that of hexagonal crosssection 404 and is configured to abut side surface 302 c of ratchetmechanism 300, thereby inhibiting locking mechanism from passingentirely through orifice 308. Flange 406 includes a notch 406 a (FIG.6). Notch 406 a is configured to act as a limiter to enable lockingmechanism 400 to rotate from a first, unlocked position, to a second,locked position by engaging limiting pin 312. Flange 406 transitions tofirst shank portion 408 having a circular cross section and a diameterless than that of flange 406 and is configured and/or dimensioned to bereceived within orifice 308 such that locking mechanism is rotatablysupported therein. Recess 410 is disposed within first shank portion 408and includes a circular cross section having a diameter less than thatof first shank portion 408. Recess 410 is configured and/or dimensionedto receive a portion of retaining pin 312 when locking mechanism 400 isfully advanced within orifice 308, thereby inhibiting locking mechanism400 from translating axially within orifice 308. First shank portion 408transitions to second shank portion 412 having a circular cross sectionand a diameter less than that of first shank section 408 such thatsecond shank portion 412 may be advanced within keyhole 210. Secondshank portion 412 transitions to leading end 414 having a sphericalcross section having a diameter complimentary to that of the circularcross section portion of keyhole 210. Leading end 414 includes opposingplanar sides 414 a, 414 b disposed thereon. Opposing planar sides 414 a,414 b reduce the diameter of leading end 414 to that of second shankportion 412 such that leading end 414 and second shank portion 412 maybe advanced within keyhole 210 when locking mechanism is in an unlockedposition (i.e., opposing planar sides 414 a, 414 b are parallel to uppersurface 302 a of ratchet mechanism 300), locking mechanism may advanceaxially within keyhole 210 as teeth 306 and teeth 208 slide past eachother as first body 100 and second body 200 rotate in a first directionallowing expandable spinal implant 10 to expand (FIG. 8). Rotation oflocking mechanism 400 may be effectuated using any suitable tool capableof transmitting rotational motion to locking mechanism 400. Rotation oflocking mechanism 400 to a second, locked position orients opposingplanar sides 414 a, 414 b normal to upper surface 302 a of ratchetmechanism 300 (FIG. 9) such that the diameter of leading end 414 abutsthe interior of keyhole 210 thereby prohibiting axial translation oflocking mechanism 300 within keyhole 210. By rotating locking mechanism400 to the locked position, teeth 208, 306 remain engaged with oneanother thereby fixing a size of expandable spinal implant 10. In otherwords, expandable spinal implant 10 is prohibited from expanding orcontracting with locking mechanism 400 in the locked position. It iscontemplated that the tool, when advanced over hexagonal cross section404 and retained within annular groove 404 a, may be used to retractratchet mechanism 300 such that teeth 208, 306 become disengaged,thereby allowing expandable spinal implant 10 to rotate in the seconddirection and contract.

With reference to FIGS. 1-11, the insertion of an expandable spinalimplant 10 into the intervertebral space during the course of a spinalsurgical procedure is described. Initially, locking mechanism 400 isplaced in a first, unlocked position (FIG. 8) by rotating lockingmechanism in a first direction using a suitable tool (not shown) engagedwith hexagonal cross section 404 of locking mechanism 400. Next, firstbody 100 is manipulated relative to second body 200 such that first andsecond bodies 100, 200 are in a first, approximated, position (FIG. 2)(e.g., closed). However, it is only necessary to perform this step iffirst and second body 100, 200 are not already in an approximatedposition. The intervertebral space is then prepared, e.g., damaged ordiseased tissue is removed. Next, expandable spinal implant 10 isaffixed to a suitable insertion instrument (not shown). It iscontemplated that the insertion tool may also be capable of engaging thehexagonal cross section 404 of locking mechanism 400. At this point,expandable spinal implant 10 may be advanced within an incision withinthe patient and thereafter, into a previously prepared intervertebralspace of the patient's spine (FIG. 10). The insertion instrument (notshown) is then manipulated to expand expandable spinal implant 10 in amedial-lateral direction to a desired location (FIG. 11) using theinsertion instrument (not shown). Medial-lateral expansion of expandablespinal implant 10 is effectuated by manipulating first and second bodies100, 200 about hinge pins 600, such that teeth 208, 306 cam, permittingrotation in the first direction, but not in a second, oppositedirection. Expansion of expandable spinal implant adjusts themedial-lateral footprint within the intervertebral space. The desiredlocation of first body 100 relative to second body 200 is selected basedon the desired medial-lateral footprint of expandable spinal implant 10.Once a desired location has been selected, locking mechanism 400 isrotated in the second, opposite direction to lock teeth 208 of secondbody 200 into engagement with teeth 306 of ratchet mechanism 300 therebylocking the position of first body 100 relative to second body 200. Ifexpandable spinal implant 10 has been expanded too far, the clinicianmay use a suitable tool (not shown) to retract ratchet mechanism 300such that teeth 208, 306 become disengaged, thereby allowing expandablespinal implant 10 to rotate or pivot in the second direction andcontract.

This process may be repeated as many times as the procedure requires,whether it be for the same expandable spinal implant 10 or for aplurality of expandable spinal implants 10 as required by the procedurebeing performed.

Expandable spinal implant 10 may be inserted using a variety of surgicaltechniques including, but not limited to, an anterior approach, ananteriolateral approach, a lateral approach, a retro-peritonealapproach, or a posterior approach. Expandable implant 10 is usable in anumber of procedures including, but not limited to, Anterior LumbarInterbody Fusion (ALIF), Posterior Lumbar Interbody Fusion (PLIF), andTransforaminal Lumbar Interbody Fusion (TLIF).

It will be understood that various modifications may be made to theembodiments of the presently disclosed expandable spinal implant.Therefore, the above description should not be construed as limiting,but merely as exemplifications of embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of thepresent disclosure.

What is claimed is:
 1. A spinal implant, comprising: first and secondbodies pivotably coupled to each other and capable of movement relativeto each other, the first and second bodies dimensioned to be installedbetween two vertebral bodies, wherein outer surfaces of each of thefirst and second bodies are adapted to engage the vertebral bodies,wherein movement of the first and second bodies is in a medial-lateraldirection relative to the two vertebral bodies; and a ratchet mechanismpivotably supported within a slot defined in a recess of the first body,the ratchet mechanism capable of engaging a portion of the second bodythereby permitting movement of the first and second bodies relative toeach other in a first direction, and inhibiting movement in a seconddirection different than the first direction.
 2. The spinal implant ofclaim 1, wherein the outer surfaces of the first body and the secondbody include ridges adapted to engage the first and second vertebralbodies.
 3. The spinal implant of claim 1, wherein at least one biasingelement is disposed within a counterbore defined in the recess of thefirst body, the at least one biasing element adapted to bias the ratchetmechanism into engagement with the second body.
 4. The spinal implant ofclaim 3, wherein the ratchet mechanism includes a first plurality ofteeth disposed thereon.
 5. The spinal implant of claim 4, wherein thesecond body includes a second plurality of teeth disposed on an interiorsurface thereon opposite the ratchet mechanism, the second plurality ofteeth configured to engage the first plurality of teeth of the ratchetmechanism.
 6. The spinal implant of claim 5, wherein the first andsecond pluralities of teeth are oriented such that the first and secondpluralities of teeth are slidably engaged in a first direction, and areprohibited from movement relative to each other in a second directiondifferent from the first direction, thereby defining a predeterminedsize of the spinal implant.
 7. The spinal implant of claim 1, whereinthe spinal implant is capable of being inserted between two vertebralbodies using a tool.
 8. The spinal implant of claim 1, wherein the firstand second bodies are capable of being manipulated relative to eachother using a tool.
 9. A method of performing surgery, comprising:positioning a first body and a second body of a spinal implant in afirst, approximated position relative to each other, the first andsecond bodies pivotably coupled to one another and capable of movementrelative to each other; inserting the spinal implant into anintervertebral space between first and second vertebral bodies, whereinouter surfaces of each of the first and second bodies of the spinalimplant are adapted to engage the first and second vertebral bodies;articulating the first body and the second body relative to each otherto obtain a desired medial-lateral footprint within the intervertebralspace; and locking a ratchet mechanism pivotably supported within a slotdefined in a recess of the first body to define a predetermined size ofthe spinal implant, the ratchet mechanism capable of engaging a portionof the second body thereby permitting movement of the first and secondbodies relative to each other in a first direction, and inhibitingmovement in a second direction different than the first direction. 10.The method of claim 9, wherein inserting the spinal implant includes thespinal implant capable of being secured to an insertion device prior toinserting the spinal implant in the intervertebral space.
 11. The methodof claim 9, wherein positioning the first body and the second body inthe first, approximated, position includes engaging a first plurality ofteeth disposed on a surface of the ratchet mechanism with a secondplurality of teeth disposed on an opposing surface of the second body,thereby permitting articulation of the first body relative to the secondbody in a first direction, but not in a second direction.
 12. The methodof claim 9, wherein inserting the spinal implant includes the spinalimplant capable of being secured to an insertion instrument.
 13. Themethod of claim 12, wherein articulating the first body relative to thesecond body includes the first body and the second body configured to bearticulated relative to one another using an insertion instrument.
 14. Aspinal implant, comprising: first and second bodies pivotably coupled toeach other and capable of movement relative to each other, the first andsecond bodies dimensioned to be installed between two vertebral bodies,wherein outer surfaces of each of the first and second bodies areadapted to engage the vertebral bodies; a ratchet mechanism pivotablysupported within a slot defined in a recess of the first body, theratchet mechanism capable of engaging a portion of the second bodythereby permitting movement of the first and second bodies relative toeach other in a first direction, and inhibiting movement in a seconddirection different than the first direction; and a locking mechanismdisposed within an orifice defined in a side surface of the ratchetmechanism and a keyhole defined in an end face of the second body. 15.The spinal implant of claim 14, wherein the locking mechanism includesfirst and second end portions, wherein the second end portion is capableof advancing axially within the keyhole in a first, unlocked position,wherein the second end portion is capable of locking the ratchetmechanism into a selected position when in a second, locked, position.16. The spinal implant of claim 15, wherein the first end portion of thelocking mechanism is attachable to a tool.
 17. A method of performingsurgery, comprising: positioning a first body and a second body of aspinal implant in a first, approximated position relative to each other,the first and second bodies pivotably coupled to one another and capableof movement relative to each other; inserting the spinal implant into anintervertebral space between first and second vertebral bodies, whereinouter surfaces of each of the first and second bodies of the spinalimplant are adapted to engage the first and second vertebral bodies;articulating the first body and the second body relative to each otherto obtain a desired footprint within the intervertebral space; andlocking a ratchet mechanism pivotably supported within a slot defined ina recess of the first body to define a predetermined size of the spinalimplant, the ratchet mechanism capable of engaging a portion of thesecond body thereby permitting movement of the first and second bodiesrelative to each other in a first direction, and inhibiting movement ina second direction different than the first direction, wherein thelocking mechanism is disposed within an orifice defined within a sidesurface of the ratchet mechanism and a keyhole defined in an end face ofthe second body, wherein the locking mechanism includes first and secondend portions, wherein the second end portion is capable of advancingaxially within the keyhole, wherein the locking mechanism is configuredto be rotated to a locked position using a tool.
 18. The method of claim17, wherein locking the ratchet mechanism further includes attaching atool to the first end portion of the locking mechanism.